Attrition

The sacrifice clause is what keeps this honest. Repeatable destruction at instant speed would be oppressive in black if it cost only mana, so the design ties each kill to a creature you already control, turning every activation into a body-for-body trade plus the black mana on top. That fuel requirement is the whole engine: feed it expendable creatures (tokens, dying triggers, anything that wants to hit the graveyard) and a single enchantment becomes an inexhaustible removal supply that grinds an opponent's board to nothing one creature at a time. The nonblack restriction is the other discipline, a tidy reminder of early-era color-pie thinking that black should not freely murder its own; it also means a black mirror neuters the card entirely. What separates this from a one-shot sacrifice effect is permanence: it survives, it keeps asking for fodder, and over a long game it converts an attrition war (the name is not subtle) into a one-sided one. The deck that wants it is one already built to leak creatures into the yard, the sacrifice-and-recur shell black has returned to for decades. Slow, mana-hungry, and entirely dependent on having something to throw into it, but in a board built to feed it, the enchantment outlasts everything across the table.